Propeller mounting



I May 16, 1933.

w. J. BLANCHARD 1,908,814

PROPELLER MOUNTING Filed Aug. '5, 1930 INVENTOR g m zfi J 54 11 46190 Patented May 16, 1933 UNITED STATES PATENT OFFICE WERNER J. BLANGHARD, 0F HEMPSTEAD,

My invention relates generally to aeronautical propellers and more particularly to aeronautical propellers having SOlld metal blades and integral therewith a central boss or hub portion Propellers thus characterlzed are usually constructed of duralumin, or a similar light weight strong alloy, or an alloy of magnesium, and are the invention of Dr. Sylvanus A. Reed.

Usually propellers of the Reed type are provided with a so-called hub sleeve. ThlS sleeve is inserted and fastened in the center bore of the pro eller hub and is so designed and constructe as to not only withstand the forces required to be exerted in mounting the propeller, but to transmit and withstand also the full driving torque of the propeller drive shaft. Usually the sleeve is an accurately machined part, co-extensive in length (whether made in one or two pieces) with the length of the center bore, and of metal harder and heavier than the alloy of the central boss or hub.

To eliminate the use of the expensive hub liner or sleeve, it has been heretofore proposed to directly key or spline the propeller drive shaft to the metal wall of the center bore of the hub. Experiments along this line have led to the abandonmentof the idea due to the fact that the metal of the hub, though hard enough to admit of the proper transmission of the driving torque, lacks sulficient hardness to withstand the forces required to be exerted in establishing the bearmg surfaces necessary to the proper mounting of the propeller on the drive shaft. Moreover, in view of the high temperature encountered at the hub mounting of an aeronautical propeller, duralumin or the like, by reason of its relatively large coefficient of expansion cannot be satisfactorily used as a direct bearing material, i. e., at the points of direct and close contact required to be established in rigidly fastening the drive shaft to the propeller hub.

The principal object of the present invention is to effect what may be termed a compromise between the prevailing or existing types of propeller mounting (expensive and relatively heavy) and that type or form of NEW YORK,

MOUNTING 1930. Serial No. 473,242.

mounting-(cheaper and lighter) heretofore tried and abandoned as unsafe. To achieve this object'it is essential that the propeller should include a hub portion of a material having substantiall the physical properties of duralumin, said hub portion having formed therein a center bore keyed throughout a substantial portion of its length for direct driving engagement with the propeller drive shaft, and means within said center bore and at opposite ends of said keyed portion and of a material having physical properties substanitally unlike the physical properties of duralumin for withstanding the the forces required to be exerted in mounting the propeller on said drive shaft. Thus constructed, the propeller is made lighted and a very substantial saving in production cost achieved thru the elimination of the necessarily machined hub sleeve or liner.

A further object of the invention is to provide a material substantially harder than duralumin mounted co-axially of the center bore at the inner end thereof for protecting the duralumin against mutilation by and as a result of the contact of a harder metal therewith during the passage of the drive shaft thru the center bore or hub opening.

Other objects and advantages of the invention will be hereinafter set forth.

In the drawing, wherein the one view rep resents a longitudinal vertical section of the hub portion of a propeller, 10 designates the propeller drive shaftand 11 the propeller hub portion which is integral with the propeller blades and is formed of solid metal, for example, duralumin or a similar. light weight strong alloy, or an alloy of magnesium. Said hub portion has formed therein a center bore 12 provided, intermediately of its ends, with splines or keys which are adapted to interfit with correspondingly formed splines or keys formed on the drive shaft. A

direct driving contact between the drive shaft l0 and the hub 11 is thus established.

At its opposite ends the center bore 12 is enlarged in diameter and interiorly threaded as indicated at 1313. The threads 13 at the inner end of the hub enlargement are adapted to receive a cone ring 14, which said ring,

cone ring 18 made fast to the drive at its inner end, is adapted to bear directly against a washer 15, said washer being splined or keyed in the same manner as the center bore, the keys and keyways being formed by a broach after the washeris assembled. In this way the keys and keyways or splines are properly aligned. The cone ring, at its outer end, or at that end remote from the washer 15,'bears directly against a cone shaped enlargement 16 either integral with or fastened to the drive shaft 10. At the opposite end of the center bore, i. e., at its outer end, a cone ring 17 similar to the cone ring 14, is threaded into the outer bore end enlargement. This cone ring 17 is adapted to bear directly against a split shaft 10 by a lock-nut 19 threaded over the outer shaft terminal. To admit of the backing of the split cone ring 18, an annular flange 20 is formed on the inner end of the lock-nut 19,

which said flange is adapted to fit behind an overhanging flange 21 formed on the split ring 18. It will thus be seen that as the nut 19 is unscrewed the flanges 20 and 21 will directly contact to withdraw the split cone ring 18 from its bearing contact with the cone ring 17 threaded in the outer end bore enlargement.

It having been found that duralumin or the like lacks sulficient hardness to withstand the forces required to be exerted in fastening the propeller to the propeller shaft, the cone rings 14, 17, and 18 and the cone shaped enlargement 16 are preferably formed of a material such as steel. This is true also of the roteetion washer 15 at the inner end of t e splined portion of the center bore. Duralumin or the like, as a material, due to its physical properties and its relatively large coefiicient of expansion, cannot be utilized where firm and intensive bearing contact is required to be maintained. It is, however, sulficiently hard and sufliciently tough to withstand the driving torque of the propeller drive shaft. The temperature condition at the hub, in the latter case, is of no moment since the inter-fitting keys or splines are made with suflicient tolerances to admit of the required expansion and contraction. Such tolerances can under no circumstances be maintained at the ends of the center bore where the propeller is fastened because of the essential requirement that the propeller be held absolutely firm and incapable of any play whatsoever even under the severe stresses of service operation.

Thru the arrangement above described, a propeller mounting roughly thirty-five percent (35%) cheaper than the conventional mounting is made possible. The co-extensive hub sleeve or liner is dispensed with and a saving in weight, of special importance in an aeronautical propeller, also achieved. Incidentally, a mounting such as above described, has been approved and accepted as a standard of equipment in propeller practice.

The function of the washer 15 is that of a protector. It protects the ends of the splines in the propeller hub proper while the propeller is being installed upon the engine crank shaft. Were it omitted the *duralumin splines or keys, due to their inherent softness as compared to steel, would in a short time, were the ropeller removed and replaced, be very muc disfigured and mutilated. No fastening, other than the contact of the cone ring 14 therewith, is required in connection with the washer. Moreover, it is impossible for any of the hub parts to work loose while the propeller is in service because the two cone seats are locked in place by the action of the two cones on the propeller drive shaft.

While I have described my invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art after understanding my invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. I aim in the appended claims to cover all such modifications and changes.

What I claim is:

1. In combination, an aeronautical propeller including a hub portion of a material having substantially the physical properties of duralumin, said hub portion having formed therein a center bore keyed throughout a substantial portion of its length for direct driving engagement with the propeller drive shaft; and means within said center bore and at opposite ends of said keyed portion and of a material having physical properties substantially like the physical properties of steel for withstanding the forces required to be having substantially the physical properties 11 of duralumin, said hub portion having formed therein a center bore keyed throughout a substantial portion of its length for direct driving engagement with the propeller drive shaft, and means within said center bore and at opposite ends of said keyed portion and of a material having a substantially smaller coeflicient of expansion than duralumin for withstanding the forces require to be exerted in mounting the propeller on the drive shaft.

3. In combination, an aeronautical propeller including a hub portion of a relatively light and soft metal such as duralumin, said hub portion having formed therein a center bore keyed throughout a substantial portion against steel for withstanding the forces required to be exerted in mounting the propeller on the drive shaft.

4. In combination, an aeronautical propeller including a hub portion of a material having substantially the physical profperties of duralumin, said hub portion having ormed therein a center bore of smaller diameter throughout the intermediate portion of its length than at its end, and said intermediate portion being in direct-driving engagement with the propeller drive shaft; and means engaging within the large diameter portions of said center bore and of a material having physical properties substantially like the physical properties of steel for withstanding the forces required to be exerted in mounting the propeller on the drive shaft.

5. In combination, an aeronautical propeller including a hub portion of a material having substantially the physical properties of duralumin, said hub portion having formed therein a center bore internally threaded and of larger diameter at its opposite ends than throughout the intermediate portion of its length, and said intermediate portion being keyed to receive the direct driving torque of the propeller drive shaft, and means engaging within the threaded portions of said center bore and of a material having physical properties substantially like the physical properties of steel for withstanding the forces required to be exerted in mounting the propeller on the drive shaft.

In combination, an aeronautical propeller including a hub portion of a material having substantially the physical properties of the duralumin, said hub portion having formed therein a center bore keyed to receive the direct driving torque of the propeller drive shaft, and a correspondingly keyed washer of a material substantially harder and tougher than duralumin mounted co-axiallyof the center bore at the inner end thereof for the protection purposes specified.

In combination, an aeronautical propeller including a hub portion of a material having substantially the physical properties of duralumin, said hub portion having formed therein a center bore keyed to receive the direct driving torque of the propeller drive shaft, a correspondingly keyed washer of amaterial substantially harder and tougher than duralumin mounted co-axially of the center bore at the inner end thereof for the purpose specified, and means within said center bore and at the opposite ends of said keyed portion and of a material similar to that of said washer for withstanding the forces required to be exerted on the hub portion in mounting it upon said drive shaft, the means at the washer end of said center bore acting jointly as aholding means for fastening said washer in place.

8. In combination, an aeronautical propeller including a hub portion having formed therein a keyed center bore by means of which the driving torque of the propeller drive shaft is directly transmitted to said propeller without the intervention of a liner, and oppositely beveled cone rings mounted co-axially of said center bore at opposite ends thereof and counter-sunk within the propeller hub and of a material having physical properties substantially like the physical properties of steel for withstanding the forces required to be exerted in mounting the propeller on said drive shaft.

9. In combination, an aeronautical propeller including a hub portion having formed therein a keyed center bore by means of which the driving torque of the propeller drive shaft is transmitted to said propeller without the intervention of a liner, means within said center bore and at opposite ends of said keyed portion, and of a material substantially harder and tougher than the material of which said hub portion is made for withstanding the forces required to be exerted in mounting the propeller on said drive shaft, and a washer of a material having substantially the physical properties of the material of which said last mentioned means is made, said washer being interposed between the inner end of the keyed portion of the center bore and the fastening means at sa d inner end.

10. In combination, a propeller including a hub of relatively soft material having a center bore keyed to the propeller drive shaft, and means at opposite ends of the bore consisting of a relatively hard material for withstand ng the stresses incident to mounting the propeller on the drive shaft.

11. In combination, a propeller including a hub portion of a relatively light material and having therein a center bore keyed throughout a substant al portion of its length to the propel drive shaft, and means at opposite ends of said keyed portion of the bore consisting of a relatively hard material for withstanding the stresses incident to mounting the propeller on the drive shaft.

12. In combination, a propeller including a hub portion of a relatively light material and having therein a center bore keyed throughout a substant a1 portion of its length to the propeller drive shaft, with tolerance therebetween to permit expansion and contraction therebetween, and means at oppos te ends of said keyed portion of the bore consisting of a relatively hard material for withstanding the stresses incident to mounting the propeller on the drive shaft.

13. In combination, a propeller including a hub portion of relatively soft material having a center bore within wh ch is adapted to be keyed a propeller shaft, and means at the inner end of said bore consisting of a relatively hard material for withstanding the wearing action which would otherwise deform the center bore u on repeated installation and removal of tile pro Her.

14. In combination, a pro er hub of rel- 5 atively light and soft materlal having a center bore for mounting on a propeller shaft," said bore having means formed therein for engagement with said shaft for transmis- -sion of torque, attaching means carried by said shaft, and meanscom rising relatively hard material attached adjacent the ends of said bore for engaging said attaching means.

In testimony whereof I hereunto aflix my signature.

WERNER J. BLANCHARD. 

